Abstract: The growth form, habitats to be invaded and the harmfulness of 42 exotic invasive plant species in Ruili Municipality, Yunnan Province were analyzed based on the investigation. The 42 exotic invasive plant species were classified into 3 categories according to their harmfulness by their distribution range and their dominance in the habitats invaded. Individually, there were 9 species, 8 species and 25 species in Grade Ⅰ, Grade Ⅱ and Grade Ⅲ of the exotic invasive plants. The damage of the 9 species in Grade Ⅰwas discussed in details. It was indicated by the investigation that the damage of the exotic invasive plants has been increased along with the deduction of biodiversity and deterioration of the natural environment in Ruili Municipality. The impact caused by the exotic invasive plants was even more evident on plantations with low coverage, and on the ecosystem suffered from severe artificial interference. It was also showed by the investigation that the species and number of the exotic invasive plants, and their harmfulness to the environment was reduced when the elevation increased. Among the exotic invasive plants, the herbaceous species and liana species showed stronger invading capacity than the woody arbor species, so the damage of the exotic invasive woody plant species was less severe.